The present invention relates to an improved flotation agent for phosphate ore which, in addition to a fatty acid as collector, comprises a mixture of ethoxylated alkylphenols.
In the flotation of phosphate ore with fatty acids according to ZA-90/9347, it is prior art that the flotation output can be improved by using, in addition to the collector (fatty acid), a dispersing agent, such as, for example, a nonylphenol with 2-5 mol of ethylene oxide (EO) and an aliphatic oxyethylated alcohol with the chain length C11-C15 which contains 2-4 mol of EO. A further improvement arises if an alcohol with the chain length C1-C15 is dissolved in the dispersing agent. This alcohol improves the emulsifiability of the dispersing agent.
Surprisingly, it has now been found that the specific concentration of a reaction product of nonylphenol and 2.75 to 3.25 mol of ethylene oxide during the flotation of phosphate from phosphate ore can be significantly reduced for the same yield and same quality if the nonylphenol used contains 9 to 13% by weight of dinonylphenol instead of the standard 2 to 5% by weight of dinonylphenol. It is also the case that the phosphate yield is even improved by using the dispersing agent according to the invention in the same concentration, without adversely affecting the P2O5 content in the flotation concentrate.
The invention thus provides a flotation agent for phosphate ore, comprising a fatty acid as collector and alkoxylated alkylphenols as dispersing agents, characterized in that the alkylphenols are composed of
a) 8 to 20% by weight of one or more dialkylphenols having alkyl radicals from 8 to 12 carbon atoms
b) 80 to 92% by weight of one or more monoalkylphenols having alkyl radicals from 8 to 12 carbon atoms, which have been alkoxylated with 2 to 6 mol of ethylene oxide.
The invention further provides for the use of a mixture of alkoxylated alkylphenols as described above as dispersing agents in the flotation of phosphate ores. In a preferred embodiment, the use takes place with fatty acids as collector.
The dispersing agent preferably comprises 9 to 15% by weight, in particular 10 to 13% by weight, of constituent a). The content of constituent b) is given by the difference to 100% by weight. The alkyl radicals are preferably linear or branched nonyl radicals. The content of ethylene oxide in constituents a) and b) is, in a further preferred embodiment, between 2 and 4 mol, in particular between 2.5 and 3.5 mol. In a further preferred embodiment, the flotation agent according to the invention does not comprise alcohols.
The fatty acid which makes up the main constituent of the flotation agent according to the invention is preferably a linear or branched monocarboxylic acid having 8 to 26 carbon atoms. For this purpose, the fatty acids known in the prior art as collectors can be used.
The flotation agent according to -the invention preferably comprises between 1 and 30% by weight of the dispersing agent. The flotation agent according to the invention is preferably used in amounts of from 100 to 1000 g/t of solid for the flotation of phosphate ores. The amount of dispersing agent according to the invention added in the case of separate collector/dispersing agent dosing is preferably between 30 and 150 g/t, in particular between 40 and 60 g/t, based on the solids charge.
The flotation agent according to the invention can, in addition to said constituents of fatty acid and dispersing agent, comprise depressants or further constituents known from the prior art. Such constituents are, for example, foaming agents and aliphatic polyglycol ethers. In addition, different depressants such as, for example, waterglass, can be used separately.